The present invention relates to polyisocyanate addition products and to composite polyisocyanate addition products and processes for their production.
The production of polyurethanes with the aid of various types of catalysts is known. In the production of polyurethane composite materials and polyurethanes made up with other materials (such as polyurethane foams covered with colored polyvinyl chloride or ABS foils or with textile coverings of cotton or leather), it has often been found that the catalysts used to produce the polyurethane damage the covering materials due to diffusion. For example, the lacquer used in furniture manufactured from molded foam parts and lacquered wood (such as chairs and sofas) in which the lacquered wood is visible may be damaged considerably by the catalyst used to produce the foam, especially in warm weather. Softening and discoloration of nitrocellulose lacquers is particularly likely to occur. Yellowing of leather and light colored textile coverings of polyurethanes (especially those based on cotton) is also known to occur as a result of diffusion of the catalyst used to produce the foam.
In the field of foam-backed foils based on PVC and ABS, distinct color changes are observed in the covering and lining materials due to separation of the activators. These changes may result in a very dark or even black discoloration even if the foils were originally light in color.